Neuroscience 2005 Abstract
| Presentation Number: | 335.14 |
|---|---|
| Abstract Title: | Effects of dopamine synthesis blockade on amphetamine-evoked behavior after unilateral nigral or cortical damage in the rat. |
| Authors: |
Paquette, M. A.*1
; Castaneda, E.1
1Psychology, Arizona State Univ., Tempe, AZ |
| Primary Theme and Topics |
Disorders of the Nervous System - Trauma -- Brain: Animal models and human studies |
| Secondary Theme and Topics | Sensory and Motor Systems<br />- Basal Ganglia<br />-- Cellular physiology, small networks, and plasticity |
| Session: |
335. Brain Trauma: Animal Models and Human Studies II Poster |
| Presentation Time: | Sunday, November 13, 2005 2:00 PM-3:00 PM |
| Location: | Washington Convention Center - Hall A-C, Board # UU96 |
| Keywords: | alpha methylparatyrosine, m-hydroxybenzylhydrazine, 6-hydroxydopamine |
Transient changes in amphetamine (AMPH) responsivity are observed in the first days after unilateral brain damage produced by infusion of 6-hydroxydopamine (6-OHDA) into the substantia nigra to deplete dopamine (DA) or by cortical ablation [Paquette et al., 2004, SfN Abstracts, 30]. We hypothesized that DA synthesis is altered during this early, transient period. To test this, we conducted dose-response studies of the effects of DA synthesis inhibitors on AMPH-evoked rotation 24 hr after unilateral brain damage. Specifically, we assessed: 1) the effects of the tyrosine hydroxylase (TH) inhibitor a-methylparatyrosine (a-MPT; 0, 10, 32, 56, 100, or 320 mg/kg, i.p.) after nigral or cortical damage, or 2) the effects of the dopa decarboxylase inhibitor m-hydroxybenzylhydrazine (NSD-1015; 0, 10, 32, or 100 mg/kg, i.p.) after nigral damage only. One day after 6-OHDA treatment, AMPH-evoked rotation was contraversive to the lesion and was resistant to synthesis inhibition by a-MPT and NSD-1015 at all doses. However, one day after cortical ablation, AMPH-evoked behavioral activation (measured as total turns in both directions) showed a dose-dependent attenuation to a-MPT. Animals tested 14 days post-6-OHDA also showed dose-dependent attenuation of AMPH-evoked rotation to synthesis blockade, presumably a measure of normal function mediated by the intact hemisphere. These data support a role for altered synthesis early after unilateral nigral or cortical damage. However, even supraphysiological levels of a-MPT did not block AMPH-evoked contraversive rotation at day 1 post-6-OHDA, leading us to speculate that other mechanisms of DA turnover are likely involved in these transient responses to AMPH (e.g. vesicular storage). This research is significant for its potential to determine the functional implications of neurophysiological events during the immediate sequelae following brain damage, which should optimize the development of early interventions. Also see: Hutchings et al., 2005 and Marsh et al., 2005, SfN Abstracts, 31.
Supported by ASU OVPR
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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